Lubricant greases are typically formulated to include a combination of lubricant base stocks with additives to provide additional desired properties. Conventionally, the combination of lubricant base stocks can include a portion of bright stock and a portion of a light neutral or heavy neutral base stock. The additives can typically include a thickening agent.
Formulating lubricant greases for cold temperature environments can present additional difficulties. Greases used in equipment in cold environments can offer increased resistance to motion of moving parts, which can lead to corresponding increases in power required to move such parts and/or increases in wear on the equipment. Additionally, during equipment startup in a cold environment, a grease may have increased resistance to movement based on the yield-stress properties of the grease. In addition to causing increased power consumption, the increased resistance to movement may lead to equipment failure due to failure to properly lubricate intended surfaces in the equipment. Reduced grease mobility can also lead to difficulties in pumping grease from a central reservoir within an equipment environment.
In order to overcome the above difficulties, greases for use in low temperature environments are typically formulated using a combination of brightstock and a base stock selected from Group III base stocks, Group IV base stocks, or Group V base stocks. While these types of base stocks can be effective for making low temperature greases, such base stocks can substantially increase the cost of the resulting grease. Thus, it would be desirable to develop grease formulations suitable for low temperature use that can be made using lower cost components.
U.S. Patent Application Publication 2008/0020958 describes grease compositions that are formulated using lubricants based on Fischer-Tropsch waxes and/or polyalphaolefin lubricants. The resulting lubricants can have desirable low temperature properties while also having low evaporation loss at high temperatures.